Two Earth-size Planets and an Earth-size Candidate Transiting the nearby Star HD 101581

• Authors: KUNIMOTO Michelle; LIN Zifan; MILLHOLLAND Sarah; VENNER Alexander; HINKEL Natalie R; SHPORER Avi; VANDERBURG Andrew; BAILEY Jeremy; BRAHM Rafael; BURT Jennifer A; BUTLER R Paul; CARTER Brad; CIARDI David R; COLLINS Karen A; COLLINS Kevin I; COLON Knicole D; CRANE Jeffrey D; DAYLAN Tansu; DIAZ Matias R; DOTY John P; FENG Fabo; GUENTHER Eike W; HORNER Jonathan; HOWELL Steve B; JANÍK Jan; JONES Hugh R A; KABATH Petr; KANODIA Shubham; LITTLEFIELD Colin; OSBORN Hugh P; O'TOOLE Simon; PAEGERT Martin; PINTR Pavel; SCHWARZ Richard P; SHECTMAN Steve; SRDOC Gregor; STASSUN Keivan G; TESKE Johanna K; TWICKEN Joseph D; VANZI Leonardo; WANG Sharon X; WITTENMYER Robert A; JENKINS Jon M; RICKER George R; SEAGER Sara; WINN Joshua
• Year of publication: 2025
• Type: Article in Periodical
• Magazine / Source: Astronomical Journal
• MU Faculty or unit: Faculty of Science
• web: https://iopscience.iop.org/article/10.3847/1538-3881/ad9266/pdf
• Doi: http://dx.doi.org/10.3847/1538-3881/ad9266
• Keywords: exoplanets; Earth-size candidate; star HD 101581
• Description: We report the validation of multiple planets transiting the nearby (d = 12.8 pc) K5V dwarf HD 101581 (GJ 435, TOI-6276, TIC 397362481). This system consists of at least two Earth-size planets whose orbits are near a mutual 4:3 mean-motion resonance, HD 101581 b ( R-p=0.956(-0.061)(+0.063 )R(circle plus) , P = 4.47 days) and HD 101581c ( R-p=0.990(-0.070)(+0.070 )R(circle plus) , P = 6.21 days). Both planets were discovered in Sectors 63 and 64 TESS observations and statistically validated with supporting ground-based follow-up. We also identify a signal that probably originates from a third transiting planet, TOI-6276.03 ( R-p=0.982(-0.098)(+0.114 )R(circle plus), P = 7.87 days). These planets are remarkably uniform in size and their orbits are evenly spaced, representing a prime example of the "peas-in-a-pod" architecture seen in other compact multiplanet systems. At V = 7.77, HD 101581 is the brightest star known to host multiple transiting planets smaller than 1.5 R (circle plus). HD 101581 is a promising system for atmospheric characterization and comparative planetology of small planets.